U.S. patent number 11,295,947 [Application Number 17/045,615] was granted by the patent office on 2022-04-05 for method for producing ozone water.
This patent grant is currently assigned to NOMURA MICRO SCIENCE CO., LTD., TOHOKU UNIVERSITY. The grantee listed for this patent is NOMURA MICRO SCIENCE CO., LTD., TOHOKU UNIVERSITY. Invention is credited to Takayuki Jizaimaru, Takeshi Sakai, Yasuyuki Shirai.
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United States Patent |
11,295,947 |
Shirai , et al. |
April 5, 2022 |
Method for producing ozone water
Abstract
Conventional ozone water is still insufficient in the removal
rate and cleaning ability of resist required in today's
semiconductor manufacturing field, and it does not fully meet the
expectation of further improvement in the effects of sterilization,
deodorization, and cleaning in the fields such as cleaning of
foodstuffs, cleaning of process equipment and tools, and cleaning
of fingers, as well as in the fields such as deodorization,
sterilization, and preservation of freshness of foodstuffs. The
above problem can be solved by defining the values of a plurality
of specific production parameters in the production of ozone water
into specific ranges.
Inventors: |
Shirai; Yasuyuki (Miyagi,
JP), Sakai; Takeshi (Miyagi, JP),
Jizaimaru; Takayuki (Kanagawa, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
TOHOKU UNIVERSITY
NOMURA MICRO SCIENCE CO., LTD. |
Miyagi
Kanagawa |
N/A
N/A |
JP
JP |
|
|
Assignee: |
TOHOKU UNIVERSITY (Miyagi,
JP)
NOMURA MICRO SCIENCE CO., LTD. (Kanagawa,
JP)
|
Family
ID: |
68386049 |
Appl.
No.: |
17/045,615 |
Filed: |
April 26, 2019 |
PCT
Filed: |
April 26, 2019 |
PCT No.: |
PCT/JP2019/017835 |
371(c)(1),(2),(4) Date: |
October 06, 2020 |
PCT
Pub. No.: |
WO2019/212037 |
PCT
Pub. Date: |
November 07, 2019 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20210163850 A1 |
Jun 3, 2021 |
|
Foreign Application Priority Data
|
|
|
|
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May 2, 2018 [JP] |
|
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JP2018-088715 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F
7/423 (20130101); C11D 3/3947 (20130101); C11D
11/0047 (20130101); H01L 21/02057 (20130101); B08B
3/08 (20130101); H01L 21/31133 (20130101); B01F
21/00 (20220101); C02F 1/68 (20130101); G03F
7/42 (20130101); B08B 3/10 (20130101); B01F
25/40 (20220101); B01F 23/811 (20220101); C11D
3/04 (20130101); B01F 23/2319 (20220101); B01F
23/20 (20220101); B08B 2203/005 (20130101); B01F
2101/4505 (20220101); B01F 2215/044 (20130101); B01F
2101/48 (20220101); B01F 23/237613 (20220101); B08B
2203/007 (20130101) |
Current International
Class: |
C11D
3/39 (20060101); B08B 3/08 (20060101); C02F
1/68 (20060101); C11D 3/04 (20060101); C11D
11/00 (20060101); G03F 7/42 (20060101); B08B
3/10 (20060101); H01L 21/02 (20060101) |
Field of
Search: |
;510/175 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
2001-035827 |
|
Feb 2001 |
|
JP |
|
2007-236706 |
|
Sep 2007 |
|
JP |
|
2009-056442 |
|
Mar 2009 |
|
JP |
|
2009-297588 |
|
Dec 2009 |
|
JP |
|
2012-000578 |
|
Jan 2012 |
|
JP |
|
01/05702 |
|
Jan 2001 |
|
WO |
|
Other References
"Eiken Techno," http://www.eiken-techno.co.jp/ and
http://www.eiken-techno.co.jp/ozonewater.html retreived on or
before May 1, 2018. cited by applicant .
"Sharp High-Concentration Ozone Production Unit," Apr. 20, 2012,
http://www.sharp.co.jp/sms/release/ozon2/ozon2.html. cited by
applicant .
"Development of Semiconductor Cleaning Technologies Using Micro-
and Nano-bubble Technologies," AIST,
http://optc.co.jp/rd-img/takahashi.pdf, pp. 1-12; Sep. 5, 2013.
cited by applicant .
ISR issued in WIPO Patent Application No. PCT/JP2019/017835, dated
Jun. 11, 2019, English translation. cited by applicant .
Written Opinion issued in WIPO Patent Application No.
PCT/JP2019/017835, dated Jun. 11, 2019, English translation. cited
by applicant.
|
Primary Examiner: Webb; Gregory E
Attorney, Agent or Firm: Greenblum & Bernstein
P.L.C.
Claims
The invention claimed is:
1. A process for producing ozone water comprising: A: preparing a
solution A in which at least one of hydrochloric acid, acetic acid,
and citric acid is added to pure water to adjust pH to a
predetermined value (pH); B: dissolving ozone gas supplied at a
predetermined supply flow rate (Fo) and a predetermined supply
pressure (Po) into solution A supplied at a predetermined supply
flow rate (Fw) and a predetermined supply pressure (Pw) to generate
solution B; and C: heating any of the pure water, the solution A,
and the solution B so that the liquid temperature of the ozone
water to be generated becomes a predetermined temperature, wherein:
(1) the predetermined value (pH) is 4 or less, (2) a concentration
(N) (g/Nm.sup.3) of ozone gas is 200 g per Nm.sup.3.ltoreq.N, (3)
Po and Pw are within the following ranges: 0.15
MPa.ltoreq.Po.ltoreq.0.695 MPa, 0.1 MPa.ltoreq.Pw.ltoreq.0.7 MPa, a
value of (Pw-Po) is within the following range: 0.005
MPa.ltoreq.(Pw-Po).ltoreq.0.2 MPa, and a relation between Po and Pw
is: Po<Pw, (4) Fo and Fw are within the following ranges: 0.25
NL/min.ltoreq.Fo.ltoreq.80 NL/min, 0.5 L/min.ltoreq.Fw.ltoreq.40
L/min, (5) the predetermined temperature within a range of from
60.degree. C. to 90.degree. C., and (6) the C: heating any of the
pure water, the solution A, and the solution B is performed at a
timing that includes at least before, after, or concurrently with
the B: dissolving ozone gas.
2. A process for producing ozone water comprising: A: preparing a
solution A in which at least one of hydrochloric acid, acetic acid,
and citric acid is added to pure water to adjust pH to a
predetermined value (pH); B: dissolving ozone gas supplied at a
predetermined supply flow rate (Fo) and a predetermined supply
pressure (Po) into solution A supplied at a predetermined supply
flow rate (Fw) and a predetermined supply pressure (Pw) to generate
solution B; and C: heating any of the pure water, the solution A,
and the solution B so that the liquid temperature of the ozone
water to be generated becomes a predetermined temperature, wherein:
(1) the predetermined value (pH) is 4 or less, (2) a concentration
(N) (g/Nm.sup.3) of ozone gas is 200 g per Nm.sup.3.ltoreq.N, (3)
Po and Pw are within the following ranges: 0.15
MPa.ltoreq.Po.ltoreq.0.695 MPa, 0.1 MPa.ltoreq.Pw.ltoreq.0.7 MPa, a
value of (Pw-Po) is within the following range: 0.005
MPa.ltoreq.(Pw-Po).ltoreq.0.2 MPa, and a relation between Po and Pw
is: Po<Pw, and (4) Fo and Fw are within the following ranges:
0.25 NL/min.ltoreq.Fo.ltoreq.80 NL/min, 0.5
L/min.ltoreq.Fw.ltoreq.40 L/min.
3. A process using an ozone water produced by the process as
defined in claim 2.
4. The method for producing ozone water according to claim 2,
wherein the C: heating any of the pure water, the solution A, and
the solution B is not performed.
Description
TECHNICAL FIELD
The present invention relates to a method for producing ozone
water, and further relates to a treatment method using ozone water
obtained in the production method and the ozone water.
BACKGROUND ART
In a field of producing functional electric devices such as
semiconductor substrates, liquid crystal displays, or organic EL
displays, and photomasks or the like used in the manufacturing
process thereof, there is a step of peel-off cleaning of
unnecessary resist from a member surface to which a resist such as
a photoresist used in the manufacturing process is attached
(hereinafter, "cleaning removal" or simply "removal" or
"cleaning"). In the resist peeling and cleaning, usually, first,
the resist is peeled off by SPM (sulfuric-acid and
hydrogen-peroxide mixture)
(H.sub.2SO.sub.4/H.sub.2O.sub.2/H.sub.2O) cleaning using a sulfuric
acid/hydrogen peroxide aqueous solution obtained by mixing sulfuric
acid and hydrogen peroxide water with respect to the surfaces of
the resist attachment members. Thereafter, wet cleaning such as APM
(mixed solution of ammonia and hydrogen peroxide) cleaning with an
aqueous solution of ammonia and hydrogen peroxide (APM), HPM (mixed
solution of hydrochloric acid, hydrogen peroxide and pure water)
cleaning with an aqueous solution of hydrochloric acid and hydrogen
peroxide (HPM), and DHF (mixed solution of hydrochloric acid,
hydrogen peroxide and pure water) cleaning with dilute hydrofluoric
acid (DHF) are performed. Thereafter, drying is performed to
complete a series of cleaning processes.
Currently, hot concentrated sulfuric acid is the mainstream for
cleaning and removing the resist, but a large amount of energy and
cost are required to dispose of the concentrated sulfuric acid, and
this is a large environmental load. In addition, the
above-mentioned other cleaning liquids have the same problem to a
greater or lesser extent.
In recent years, there has been proposed a method of using ozone
water as an alternative, which has fewer contaminants than
conventional cleaning and changes into harmless substances over
time (less residual chemicals)
To improve the cleaning effect of ozone water, the following
methods have been proposed:
(1) To improve the ozone concentration (dissolved ozone
concentration) in ozone water (e.g., PTL 1: Japanese Laid-Open
Patent Application No. 2012-578), and
(2) To form high temperature ozone water (e.g., PTL 2: Japanese
Laid-Open Patent Application No. 2009-56442, Non-PTL 1, Non-PTL
2.
PTL 1 describes in FIG. 2, ozone waters having ozone concentrations
of 347 mg/L and 370 mg/L, although there is no description of
temperature. PTL 2 describes in FIG. 3, high temperature ozone
waters having an ozone water temperature of 50.degree. C., with an
ozone concentration of ozone water of 135 mg/L, and an ozone water
temperature of 80.degree. C. with an ozone concentration of ozone
water of 85 mg/L.
Non-PTL 1 describes high temperature ozone water having an ozone
water temperature of 70.degree. C. with an ozone concentration of
ozone water of 200 mg/L. Non-PTL 2 describes high temperature ozone
water having an ozone water temperature of 75.degree. C. with an
ozone concentration of ozone water of 120 mg/L.
PATENT LITERATURE
PTL 1: Japanese Laid-Open Patent Application No. 2012-578 PTL 2:
Japanese Laid-Open Patent Application No. 2009-56442
NON PATENT LITERATURE
Non-PTL 1: "Eiken Techno" HP:http://www.eiken-techno.co.jp/
HP:http://www.eiken-techno.co.jp/ozonewater.html Non-PTL 2: "Sharp
High-Concentration Ozone Production Unit" Apr. 20, 2012
HP:http://www.sharp.co.jp/sms/release/ozon2/ozon2.html Non-PTL 3:
"Development of Semiconductor Cleaning Technologies Using Micro-
and Nanobubble Technologies" AIST
http://optc.co.jp/rd-img/takahashi.pdf.
SUMMARY OF INVENTION
Technical Problem
However, the low-temperature ozone water having the concentrations
described in P TL 1 and the high-temperature ozone waters having
the degree of ozone concentration described in PTL 2 and Non-PTL 1
and 2, are still insufficient in the removal rate and the cleaning
power of the resist required in the field of semiconductor
manufacturing today. They also do not fully meet the expectation of
further improvement of sterilization, deodorization, and cleaning
effects in such fields as cleaning of foodstuffs, cleaning of
process equipment and tools, and cleaning of fingers, as well as in
such fields as deodorization, sterilization, and preservation of
freshness of foodstuffs.
The reason for this is that, in the above-mentioned conventional
method for producing ozone water, only so-called partial
optimization is performed in order to optimize a part of the ozone
water production conditions (production parameters) for each
problem as described above, and the overall optimization is not
performed in the organic relation between the kinds of parameters
sufficient for the production of ozone water. For this reason, at
the present stage, it is used only in a limited manner, even if it
is used, and it has not been widely used in practical use.
Moreover, in the conventional method, a large-sized apparatus is
inevitably required for producing high-temperature and
high-concentration ozone water.
The present invention has been made in view of the above-mentioned
points, and has been made on the basis of the finding of a specific
experimental result in the process of a number of try-and-errors of
trial manufacture, confirmation experiment, analysis and review to
find out what parameters of manufacturing parameters (sometimes
referred to as "production parameters") related to the production
of ozone water should be specified in what values, and all of the
constituent materials and related parameters should be used to find
out the optimum conditions so that the ozone concentration of ozone
water can be raised to a wider practical use and the treatment
target material can be substantially maintained at a high
temperature for a sufficient time to properly treat the treatment
target material in a high temperature state.
One object of the present invention is to provide a method for
producing a high concentration ozone water at a low temperature to
a high temperature in order to achieve overall optimization, a
resist treatment method using a high concentration ozone water at a
low temperature to a high temperature obtained by the production
method.
Another object of the present invention is to provide a method for
producing a high concentration heated ozone water capable of
producing heated ozone water having extremely high concentration of
(dissolved) ozone by suppressing attenuation of dissolved ozone
concentration in high concentration ozone water, a high
concentration heated ozone water obtained by the production method,
and a resist treatment liquid using the same.
Another object of the present invention is to provide a method for
producing high concentration ozone water of low temperature to high
temperature, which is more excellent in realizing high
concentration of low temperature to high temperature suitable for
versatility, and which requires no enlargement of the apparatus but
facilitates simplification of the apparatus, and a resist treatment
method using high concentration ozone water of low temperature to
high temperature obtained by the method.
Another object of the present invention is to provide an ozone
water that can fully meet the expectations of further improvements
in disinfecting, deodorizing, and cleaning effects in the fields
such as cleaning of foodstuffs, cleaning of processing equipment
and tools, cleaning of fingers, and also in the fields such as
deodorizing, disinfecting, and maintaining freshness of foods.
Solution to Problem
One aspect of the invention lies in a process for producing ozone
water comprising the following steps:
Step A: a step of preparing a solution A in which at least one of
hydrochloric acid, acetic acid, and citric acid is added to pure
water to adjust pH to a predetermined value (pH);
Step B: a step of dissolving ozone gas supplied at a predetermined
supply flow rate (Fo) and a predetermined supply pressure (Po) into
solution A supplied at a predetermined supply flow rate (Fw) and a
predetermined supply pressure (Pw) to generate solution B; and Step
C: a step of heating any of the pure water, the solution A, and the
solution B so that the liquid temperature of the ozone water to be
generated becomes a predetermined temperature, wherein: (1) the
predetermined value (pH) in Process A is 4 or less, (2) a
concentration (N) (g/Nm3) of ozone gas is within a range of 200 g
per Nm3.ltoreq.N, (3) Po and Pw are within the following ranges:
0.15 MPa.ltoreq.Po.ltoreq.0.695 MPa, 0.15 MPa<Pw.ltoreq.0.7 MPa,
a value of (Pw-Po) is within the following range: 0.005
MPa.ltoreq.(Pw-Po).ltoreq.0.2 MPa, and, a relation between Po and
Pw is: Po<Pw; (4) Fo and Fw are within the following ranges:
0.25 NL/min.ltoreq.Fo.ltoreq.80 NL/min 0.5
L/min.ltoreq.Fw.ltoreq.40 L/min, (5) the predetermined temperature
in Step C is within a range of from 60.degree. C. to 90.degree. C.,
and (6) Step C is performed at a timing that includes at least
before, after, or concurrently with Step B. Said one aspect of the
present invention also lies in ozone water obtained by the
production method and a treatment liquid or the treatment liquid
using the same.
Another aspect of the invention lies in a process for producing
ozone water comprising the following steps:
Step A: a step of preparing a solution A in which at least one of
hydrochloric acid, acetic acid, and citric acid is added to pure
water to adjust pH to a predetermined value (pH);
Step B: a step of dissolving ozone gas supplied at a predetermined
supply flow rate (Fo) and a predetermined supply pressure (Po) into
solution A supplied at a predetermined supply flow rate (Fw) and a
predetermined supply pressure (Pw) to generate solution B; and Step
C: a step of heating any of the pure water, the solution A, and the
solution B so that the liquid temperature of the ozone water to be
generated becomes a predetermined temperature, wherein: (1) the
predetermined value (pH) in Step A is 4 or less, (2) a
concentration (N) (g/Nm3) of ozone gas is within a range of 200 g
per Nm3.ltoreq.N, (3) Po and Pw are within the following ranges:
0.15 MPa.ltoreq.Po.ltoreq.0.695 MPa, 0.15 MPa<Pw.ltoreq.0.7 MPa,
a value of (Pw-Po) is within the following range: 0.005
MPa.ltoreq.(Pw-Po).ltoreq.0.2 MPa, and, a relation between Po and
Pw is: Po<Pw; and (4) Fo and Fw are within the following ranges:
0.25 NL/min.ltoreq.Fo.ltoreq.80 NL/min 0.5
L/min.ltoreq.Fw.ltoreq.40 L/min. Said another aspect of the present
invention also lies in ozone water obtained by the production
method and a treatment liquid or a treatment method using the
treatment liquid using the same.
Note that, in the above description, "MPa" represents megapascal in
unit notation, and hereinafter it may be referred to as "MP" in
some cases.
"g/Nm3" represents the gas concentration in mass per unit volume in
the standard state, and in the present application, the measured
gas concentration (value at temperature and pressure at the time of
measurement) is converted into the standard gas concentration in
mass. "NL/min" is the measured value of the gas flow rate "L/min"
per unit time (minutes) (value at temperature and pressure at the
time of measurement) converted into the value in the normal state.
In the relevant instrument installed in the ozone water production
and supply system used in the experiment described later, a value
automatically converted to a standard state value is displayed.
Advantageous Effects of Invention
According to the present invention, it is possible to provide a
method for producing high-temperature and high-concentration ozone
water having an overall optimization, a high-temperature and
high-concentration ozone water obtained by the production method, a
treatment liquid using the same, and a treatment method using the
same.
Separately, according to the present invention, it is possible to
provide a method for producing a high-concentration ozone water
having an overall optimization, a high concentration of ozone water
obtained by the production method, a treatment liquid using the
same, and a treatment method using the same.
Further, according to the present invention, it is possible to
provide a method for producing ozone water capable of producing
ozone water of extremely high ozone concentration by suppressing
the attenuation of ozone concentration in ozone water, ozone water
obtained by the production method and a treatment liquid or a
treatment method using the treatment liquid.
Other features and advantages of the present invention will become
apparent from the following description taken in conjunction with
the accompanying drawings. In the accompanying drawings, the same
or similar components are denoted by the same reference
numerals.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings are included in and constitute a part of
the specification, and illustrate embodiments of the invention and
are used to describe the principles of the invention together with
its description.
FIG. 1 is a schematic configuration diagram for explaining a
configuration of an ozone water production and supply system used
in an experiment of the present invention.
FIG. 2 is a graph showing the results of experiments in the present
application.
FIG. 3 is a graph showing the results of Experiment 1 in the
present application.
FIG. 4 is a graph showing the results of Experiment 2 in the
present application.
FIG. 5 is a graph showing the results of Experiment 3 in the
present application.
FIG. 6 is a graph showing the results of Experiment 4 in the
present application.
FIG. 7 is a graph showing the results of Experiment 5 in the
present application.
FIG. 8 is a graph showing the results of Experiment 6 in the
present application.
FIG. 9 is a graph showing the results of Experiment 7 in the
present application.
FIG. 10 is a graph showing the results of Experiment 8 in the
present application.
FIG. 11 is a graph showing the results of Experiment 9 in the
present application.
FIG. 12 is a graph showing the results of Experiment 10 in the
present application.
FIG. 13 is a graph showing the results of Experiment 11 in the
present application.
DESCRIPTION OF EMBODIMENTS
FIG. 1 is a schematic diagram illustrating one configuration of a
preferred example of an embodiment of production and supply system
100 of high-temperature and high-concentration ozone water of the
present invention.
Since the configuration of the ozone water production and supply
system 100 is the same as that of the experimental apparatus used
for examining the present invention, FIG. 1 will be used in the
following description of Examples and Comparative Examples.
FIG. 2 is a graph for explaining a typical example of data
supporting the present invention, which is obtained by
systematically conducting a number of experiments repeatedly and
systematically from a multi-viewpoint using the production and
supply system 100 for high-temperature and high-concentration ozone
water shown in FIG. 1. The horizontal axis represents the ozone gas
supply pressure (MP), and the vertical axis represents the ozone
water concentration (ppm).
As will be apparent from the following description, the present
invention is based on the finding by the inventors of the present
application that, when the ozone gas supply pressure (MP) is 0.15
or more as shown in FIG. 2, experimental results can be obtained in
which the ozone concentration in the ozone water to be produced
rises more rapidly than in the case where the ozone gas supply
pressure (MP) is less than 0.15, by setting certain specific
numerical values for some specific production parameters.
Specifically, the experimental results having the tendency shown in
FIG. 2 is obtained by conducting the following steps:
(Step A): A solution A is prepared in which at least one of
hydrochloric acid, acetic acid, and citric acid is added to pure
water to adjust the pH to a predetermined value (pH);
(Step B): Ozone gas supplied at a predetermined supply flow rate
(Fo) and at a predetermined supply pressure (Po) is supplied at a
predetermined supply flow rate (Fw) to dissolve the solution A in
the solution B at a predetermined supply pressure (Pw); and
(Step C): Heat so that the temperature of the produced ozone water
reaches a predetermined temperature,
wherein when ozone water is produced by the above-mentioned
processes,
(a) The pH value in Step A is set to 4 or less,
(b) The concentration N (g/m3) of the ozone gas in Step B is 200
g/m3.ltoreq.N,
Po and Pw is within the following ranges:
0.15 MPa.ltoreq.Po.ltoreq.0.695 MPa,
0.15 MPa<Pw.ltoreq.0.7 MPa
The value of (Po-Pw) has the following relation:
0.005 MPa.ltoreq.Po-Pw.ltoreq.0.2 MPa,
And Fo and Fw are within the following ranges:
0.25 NL/min.ltoreq.Fo.ltoreq.80 NL/min
0.5 L/min.ltoreq.Fw.ltoreq.40 L/min,
(c) Predetermined temperature in Step C is within the range of from
60.degree. C. to 90.degree. C. and,
(d) Step C is performed at a timing that includes at least before,
after, or at the same time as Step B.
Also, even if the above Step C is omitted, the experimental result
of the tendency shown in FIG. 2 can be obtained in the same manner.
However, it is possible to further increase the removal efficiency
of the resist and the like, the detergency of the contaminant and
the sterilizing power by utilizing the ozone water obtained by
carrying out the process procedure including the above Step C and
the production conditions.
As shown in FIG. 2, the increasing tendency of the concentration of
the ozone water greatly changes between the low pressure side and
the high pressure side of a boundary of 0.15 MPa of the ozone gas
pressure (ozone supply pressure: Po). That is, with an increase in
the ozone gas pressure at a boundary of 0.15 MPa, the rate of
increase in the ozone water concentration on the low pressure side
is moderate, whereas the rate of increase in the ozone water
concentration on the high pressure side is remarkably large.
Generally, when a dilute solution (dilute aqueous solution)
containing a volatile solute (ozone) is in equilibrium with the gas
phase, obeying Henry's law, the partial pressure (p) of the solute
is proportional to the concentration (c) in the solution.
However, the three measurement points X1, X2, and X3 shown in FIG.
2 are substantially on the first-order dashed line A, while the
measurement points X4 and X5 are greatly deviated from the
first-order dashed line A.
The three measurement points X3, X4 and X5 have not yet been
technically determined whether they should be viewed as being
substantially on the first-order dashed line B (first-order
approximation) or they should be viewed as being substantially on
the second-order dashed line C (second-order approximation).
In any case, under the above production conditions, why the
tendency shown in FIG. 2 is seen is not yet elucidated, but it is
speculated to be caused by, in addition to the production
conditions of (a), (b) and (c) described above, the presence of
lifetime of ozone as a solute in water as a solvent.
Furthermore, various acids were tried as the acid to be used for
adjusting the pH value, and as a result, the tendency shown in FIG.
2 was not obtained with nitric acid or the like, but the tendency
shown in FIG. 2 was remarkably obtained with hydrochloric acid,
acetic acid, and citric acid. Accordingly, it is considered that
the influence of these acids may be a cause.
Alternatively, it is conceivable that the ozone concentration in
the ozone water produced by the ozone water production method of
the present invention may not be in a sufficiently dilute state to
conform to Henry's law.
In the present invention, the Step A is performed at least before
the Step B. Further, the Step B may be performed before or after
the Step C, or simultaneously with at least a portion of the step
C. Preferably, it is desirable to carry out said Step B after said
Step C.
It is preferable that the Step B is started at the same time as the
start of the Step C or after the start of the Step C, and is
performed overlapping with the Step C. Further, the end of the Step
B is preferably after or at the end of the Step C.
Next, a high-temperature high-concentration ozone water production
and supply system 100 of the present invention shown in FIG. 1 will
be described.
The ozone water production and supply system 100 includes a hot
water production module unit 101, an ozone gas dissolving module
unit 102, and an ozone water supply module unit 103.
In the example of FIG. 2, the ozone water supply module unit 103 is
provided, but the ozone water production and supply system
according to the present invention does not necessarily include the
ozone water supply module unit 103.
The hot water production module unit 101 includes a pH adjustment
unit 101-1 and a heating unit 101-2. The hot water production
module unit 101 is provided with a water solvent supply line 104
for supplying pure water such as ultrapure water from the
outside.
The water solvent supply line 104 is, for convenience of
description, illustrated as divided into three water solvent supply
line portions (104-1 to 104-3) from the upstream side.
The pH adjustment unit 101-1 includes a flow rate adjustment valve
127, a static mixer 128, a conductivity meter 129, and a chemical
supply device 130.
The chemical supply device 130 includes a chemical solution tank
124, a part of a chemical supply line 125, and a pump 126.
For convenience of description, the chemical supply line 125 is
shown as divided into three chemical supply line portions (125-1 to
125-3) from the upstream side.
The water solvent supply line 104 is disposed in the ozone water
production and supply system 100 so as to supply heated water
heated to a predetermined temperature to the ozone gas dissolving
module unit 102 via the heating unit 101-2.
The water solvent supply line 104 supplies pure water such as
ultrapure water from outside the production and supply system 100
of ozone water to the pH adjusting unit 101-1, and supplies the pH
adjusted pure water to the heating unit 101-2.
The water solvent flowing through the water solvent supply line 104
is heated to a predetermined temperature by heating means 123, if
necessary.
A flow meter (F1) 108 is provided at a predetermined position of
the water solvent supply line portion 104-2 on the upstream side of
the water solvent supply line 104, and a thermocouple (T1) 109, a
static mixer 128, a conductivity meter 129, and a pH meter 134 are
provided at predetermined positions of the water solvent supply
line portion 104-3 on the downstream side of the water solvent
supply line 104.
The thermocouple (T1) 109 is used for measuring the temperature of
the water solvent flowing through the water solvent supply line
portion 104-3, and is also used for monitoring whether or not the
temperature of the water solvent has reached a desired
temperature.
The static mixer 128 is a static type mixer for stirring and mixing
ultrapure water supplied from the water solvent supply line portion
104-1 and a chemical solution such as citric acid supplied from the
chemical supply line portion 125-3 into a uniform solution.
The downstream side of the water solvent supply line portion 104-3
communicates with the ozone gas dissolution module unit 102.
The flow rate adjustment valve 127 is a valve for adjusting a flow
rate of the chemical solution supplied from the chemical supply
line portion 125-3 so that the ultrapure water supplied from the
water solvent supply line portion 104-1 and the chemical solution
supplied from the chemical supply line portion 125-3 have a
predetermined mixing ratio.
The conductivity meter 129 is a measuring unit that monitors
whether or not the conductivity of the chemical-containing water
solvent flowing through the water solvent supply line portion
104-2, which has been formed by stirring and mixing the ultrapure
water and the chemical solution by the static mixer 128 into a
uniform solution, is a desired value. The conductivity meter 129
can make measurement not only when necessary but also when the
agent-containing water solvent is flowing, either intermittently or
continuously.
At a timing when the data measured by the conductivity meter 129 is
sent to a predetermined control device (not shown), a control
signal for controlling the pumping amount of the pump 126 or/and
the valve opening of the flow rate adjustment valve 127 is output
from the control device and transferred to the pump 126 or/and the
flow rate adjustment valve 127. As a result, the conductivity of
the water solvent flowing through the water solvent supply line 104
can be maintained or changed to a predetermined value.
The ozone gas dissolving module unit 102 includes an ozone gas
dissolving device 102-1.
The ozone gas dissolving device 102-1 has a structure in which a
portion of the ozone gas supply line 106 is disposed and, ozone gas
flowing through the ozone gas supply line 106 is dissolved in a
water solvent supplied to the ozone gas dissolving device 102-1 by
the water solvent supply line 104.
In the present invention, the ozone gas can be produced by the
following production method, but in particular, a discharge method
is preferred because the adjustment of the supply pressure is easy
and a high concentration of ozone gas is obtained. The reason is
that when the ozone gas concentration increases, the ozone water
concentration also increases. The resist removal rate by ozone
water is improved almost linearly in proportion to the supplied
ozone gas concentration, and the detergency and sterilization power
are also improved (Non PTL 3).
1. Discharge method
The silent discharge method and the creeping discharge method have
been used practically mainly from the principle of the
discharge.
(1) An oxygen-containing gas is flowed between a pair of electrodes
arranged in a parallel plate shape or a coaxial cylinder shape, and
an alternating high voltage is applied to cause discharge in the
oxygen-containing gas to generate ozone.
One or both surfaces of the pair of electrodes must be coated with
a dielectric, such as glass. The discharge is generated in the gas
(air or oxygen) as the charge on the dielectric surface alternates
between positive and negative.
(2) Creeping discharge method is a method of using a planar
electrode whose surface is coated with a dielectric such as
ceramics, placing a linear electrode on the surface of the
dielectric, and applying an AC high voltage between the flat
electrode and the linear electrode to form a discharge on the
surface of the dielectric to generate ozone. This method is called
a creeping discharge method, because the discharge generated on the
surface of the dielectric is called a creeping discharge.
2. Electrolytic Method
A method of placing a pair of electrodes with an electrolyte
membrane sandwiched therebetween, in water, and applying a DC
voltage between the electrodes to cause electrolysis of water to
generate ozone together with oxygen in the oxygen-generation
side.
A practical electrolytic ozone generator uses porous titanium with
a platinum catalyst layer in the cathode, porous titanium with a
lead dioxide catalyst layer in the anode, and a perfluorosulfonate
cation exchange membrane as the electrolyte membrane. Electrolytic
method can generate high-concentration ozone of 20% by weight or
more. 3. Ultraviolet Lamp Method Ultraviolet rays are applied to
air to generate ozone. Usually, a mercury lamp is used as a
ultraviolet lamp.
The ozone gas supply line 106 is shown as divided into three ozone
gas supply line portions 106-1 to 106-3 for convenience of
explanation.
Pressure gauge (P3) 110 is provided at a predetermined position of
the ozone gas supply line portion 106-1, the ozone gas supply line
portion 106-2 and the ozone gas supply line portion 106-3 are
connected via a pressure regulating valve 118.
The downstream side of the ozone gas supply line portion 106-3 may
be connected to an ozone gas treatment system, and may be changed
into harmless and exhausted, or may be connected to a recycle type
ozone gas supply device to have a facility configuration for
reusing ozone gas.
The pressure regulating valve 118 may be a valve of simple ON-OFF
operation having a constant opening size, or it may be a valve
capable of adjusting the size of the opening arbitrarily or
stepwisely.
The ozone gas supply line portion 106-1 and the ozone gas supply
line portion 106-2 communicate with an ozone gas dissolving means
107 provided inside the ozone gas dissolving device 102-1.
The concentration (N) of the ozone gas supplied by the ozone gas
supply line portion 106-1 is determined according to the ozone
concentration of the ozone water to be produced, but is generally
desirably higher.
In the present invention, it is preferable that the concentration
(N) of the ozone gas is desirably within a range of the following
formula (1). 200 g/Nm3.ltoreq.N (1)
In the ozone gas dissolving means 107, the ozone gas supplied by
the ozone gas supply line 106 and the water solvent supplied by the
water solvent supply line 104 come into gas-liquid contact with
each other to form ozone water.
As the ozone gas dissolving means 107, various types may be
employed as long as they meet the object of the present invention.
Among them, it is preferable to employ a dissolution means using a
membrane dissolution method.
As a membrane dissolution method, it is preferable to employ a
method in which water is flowed through a porous Teflon (registered
trademark) membrane (septum: hollow fiber membrane), and ozone gas
is flowed outside the membrane to absorb ozone into water to
produce ozone water.
As a device for dissolving ozone gas in a water solvent, in
addition to the ozone gas dissolving device 102-1 of the type shown
in FIG. 1, the following devices may be employed.
(1) Ozone Gas Dissolving Device Using Bubble Dissolving Method
(Bubbling Method)
Ozone gas dissolving device of a type which blows ozone gas from
the lower part of the water tank, or of a type which uses an
ejector method of blowing ozone gas into a narrow part provided in
a part of the piping of the water, or a method of stirring water
and ozone gas with a pump
(2) Ozone Gas Dissolving Device Using Bubble-Free Gas Dissolving
Method
This method uses a SPG Membrane: a shirasu porous glass membrane.
Although SPG membranes have hydrophilic inner wall surfaces, there
is also a SPG membrane in which the inner wall surface is
hydrophobized. Which one to use is preferably selected depending on
its purpose.
(3) Ozone Gas Dissolving Device Using Packed Bed Dissolving
Method
Ozone gas dissolving device using a method of flowing water from
the upper part of the packed bed and flowing ozone gas from the
lower part of the packed bed to dissolve ozone in the packed bed in
a gas-liquid counter-current manner.
In any of the above-mentioned ozone gas dissolving device, it is
important to devise to make the gas-liquid contact area as large as
possible from the viewpoint of ozone water generation
efficiency.
The ozone water formed in the water solvent supply line 104 is
supplied to a surface to be processed of a member to be processed,
such as a semiconductor substrate, through the ozone water supply
line 105.
A pressure gauge (P1) 111, an ozone water concentration meter 112,
a pressure gauge (P2) 113, and an ozone water concentration meter
114 are provided at predetermined positions of the ozone water
supply line portion 105-1 from the upstream side.
Although the pressure gauge (P1) 111 and the ozone water
concentration meter 112 can be essentially replaced with each
other, it is preferable to provide the ozone water concentration
meter 112 at a position as close as possible to the ozone gas
dissolving means 107 within a design allowable range in order to
measure the ozone concentration of the ozone water immediately
after it is generated by the ozone gas dissolving means 107.
An ozone water supply line 105 for supplying ozone water generated
in the ozone gas dissolving module unit 102 is connected to the
ozone water supply unit 103.
The ozone water generated in the ozone gas dissolving module unit
102 is flowed to a predetermined position of the ozone water supply
unit 103 through the ozone water supply line 105.
In FIG. 1, the ozone water supply line 105 is composed of six ozone
water supply line portions (105-1 to 105-6) for convenience of
explanation.
The ozone water supply line portion 105-1 and the ozone water
supply line portion 105-2 communicate with each other via a
three-way open-close valve 119. The ozone water supply line portion
105-2 and the ozone water supply line portion 105-4 communicate
with each other via the open-close valve 120. A nozzle 122 is
provided at the downstream end of the ozone water supply line
portion 105-4. The ozone water supply line portion 105-3 extends
from the three-way open-close valve 119 and is connected to the
open-close valve 121. An ozone water supply line portion 105-5 is
connected to the downstream end of the open-close valve 121. A
thermocouple (T2) 115 and a flow meter (F2) 116 are provided at
predetermined positions of the ozone water supply line portion
105-5 from the upstream side. Near the discharge port of the nozzle
122, a nozzle thermometer (T3) for measuring the temperature of the
ozone water discharged is provided.
Although the ozone water supply line 105 is composed of six ozone
water supply line portions (105-1 to 105-6) in FIG. 1, in another
preferred embodiment, the three-way open-close valve 119 and the
ozone water supply line portions 105-3, 105-5, and 105-6 are
unnecessary. In this embodiment, the thermocouple (T2) 115 for
measuring the temperature of the ozone water flowing through the
ozone water supply line 105 and the flow meter (F2) for measuring
the flow rate are provided at desired positions of the ozone water
supply line 105-2 provided on the upstream side of the open-close
valve 120, as necessary.
Next, an example of a suitable procedure for producing and
supplying ozone water by the production and supply system 100 of
high-temperature high-concentration ozone water will be
described.
The ultrapure water supplied as indicated by an arrow (A1) from the
water solvent supply line 104 connected to a house line (not shown)
is mixed uniformly with a predetermined acid solution (chemical
solution) such as citric acid supplied from the chemical solution
tank 124 through the chemical supply line 125 in the static mixer
128 to have conductivity adjusted to a predetermined value to
dissolve ozone gas.
The flow rate of the chemical solution is controlled to be a
predetermined value by adjusting the pump force of the pump 126 and
the valve opening degree of the flow rate adjustment valve 127.
The value of the conductivity to be adjusted is measured by the
conductivity meter 129. The water solvent (A) whose conductivity is
adjusted is sent to the heating means 123 through the water solvent
supply line portion 104-2, and is heated to a predetermined
temperature if necessary.
The flow rate (F1) of the water solvent (A) flowing through the
water solvent supply line portion 104-2 is measured by a flow meter
(F1) 108.
As indicated by the arrow A2, the water solvent (B) heated if
necessary is output from the heating means 123 to the outside of
the hot water production module unit 101 via the water solvent
supply line portion 104-3.
The temperature (T1) of the water solvent (B) is measured by a
thermocouple (T1) 109.
The water solvent (B) is supplied to the ozone gas dissolving
device 102-1 via the water solvent supply line portion 104-3 to
fill a predetermined space region provided in the ozone gas
dissolving device 102-1.
The supply pressure of the water solvent (B) to be supplied into
the ozone gas dissolving device 102-1 is measured by a pressure
gauge (P0) 111-1.
The pressure of the ozone water output from the ozone gas
dissolving device 102-1 is measured by a pressure gauge (P1) 111-2.
Pressure gauge (P1) 111-2 is for measuring the pressure of the
ozone water immediately after output from the ozone gas dissolving
device 102-1, and is preferably provided as close as possible to
the ozone gas dissolving device 102-1 so long as the design
allows.
On the other hand, the ozone gas is guided into the ozone gas
dissolving device 102-1 through the ozone gas supply line portion
106-1.
An ozone gas dissolving means 107 is provided in the middle of the
ozone gas supply line 106, and the gas supply pressure (Po) of the
ozone gas supplied to the ozone gas dissolving means 107 is
measured as a value P3 by a pressure gauge (P3) 110. Therefore, it
is preferable that the pressure gauge P3 110 be provided as close
as possible to the ozone gas dissolving means 107 so long as the
design allows.
The gas supply pressure (Po) of the ozone gas supplied to the ozone
gas dissolving means 107 is controlled by adjusting the degree of
opening of the pressure regulating valve 118.
The ozone gas dissolving means 107 shown in FIG. 1 has a pipe
structure in a spiral shape in order to have a large gas-liquid
contact surface as much as possible in a limited length in the flow
direction of the gas, but the present invention is not limited to
this shape and structure, and it may have any shape and structure
as long as it can be accommodated in the inner space (filled with
water solvent) of the ozone gas dissolving device 102-1, and it has
a gas-liquid contact surface area sufficient to achieve the object
of the present invention.
Further, in FIG. 1, although an example of a structure in which the
inner space of the ozone gas dissolving device 102-1 is filled with
water solvent is shown, a structure may be employed in which the
inner space of the ozone gas dissolving device 102-1 is filled with
ozone gas, and the supply line of the water solvent passes
therethrough.
One of the constitutional requirements of the present invention is
that the gas supply pressure (Po) and the supply flow rate (Fo) of
the ozone gas supplied to the ozone gas dissolving means 107 in the
ozone gas dissolving device 102-1 through the ozone gas supply line
portion 106-1 are closely related to the supply pressure (Pw) and
the supply flow rate (Fw) of the water solvent supplied to the
ozone gas dissolving device 102-1 through the water solvent supply
line 104, respectively.
In the present invention, the values of Po and Pw are specified in
the following ranges: 0.15 MPa.ltoreq.Po.ltoreq.0.695 MPa (2) 0.15
MPa<Pw.ltoreq.0.7 MPa (3)
Preferably, the value of Po is in the following range of 0.175
MPa.ltoreq.Po.ltoreq.0.695 MPa (2') Po and Pw preferably have the
following relationship: 0.005 MPa.ltoreq.(Pw-Po).ltoreq.0.2 MPa,
(4) Po<Pw (5)
By making the relationship of Formula (5), it is possible to
suppress or prevent the generation of bubbles in the water
solvent.
The value of Fo and Fw value are preferably is in the following
ranges: 0.25 NL/min.ltoreq.Fo.ltoreq.80 NL/min (6) 0.5
L/min.ltoreq.Fw.ltoreq.40 L/min (7) The value of Fo is preferably,
0.5 NL/min.ltoreq.Fo.ltoreq.80 NL/min (6') It is even more
preferable to set Fo in the above range.
In the system 100 of FIG. 1, the gas supply pressure (Po) of the
ozone gas is measured as a value P3 by a pressure gauge (P3) 110,
the supply flow rate (Fo) of the ozone gas is measured as a value
F3 by a flow meter (F3) 131.
The supply pressure (Pw) of the water solvent is measured as the
value Po by the pressure gauge (P0) 111-1 or as a value P1 by the
pressure gauge (P1) 111-2, and the supply flow rate (Fw) of the
water solvent is measured as a value F1 by the flow meter (F1)
108.
Undissolved ozone gas may be discarded to the outside as indicated
by the arrow A9 through the ozone gas supply line portion 106-3, or
may be circulated from the ozone gas supply line portion 106-1 to
the ozone gas dissolving means 107 as indicated by the arrow A8 to
be reused.
The ozone water generated in the ozone gas dissolving module unit
102 is supplied to a predetermined position of the ozone water
supply unit 103 through the ozone water supply line 105.
Ozone water formed in the water solvent supply line 104, when it is
supplied to the surface to be treated of the member to be treated
such as a semiconductor substrate, is supplied to the nozzle means
122 via the ozone water supply line portion 1051-1, 105-2, and
105-4, and is sprayed onto the surface to be treated of the member
from the discharge port of the nozzle means 122.
When no experiment is conducted to treat the surfaces of the member
to be treated, the flow path direction of the three-way open-close
valve 119 is switched so that the generated ozone water flows out
in the direction of the arrow A7 through the ozone water supplying
line portions 105-3, 105-5, and 105-6.
The supply pressure of the ozone water flowing through the ozone
water supply line portion 105-3 is measured by the pressure gauge
131 as necessary.
The supply pressure of ozone water flowing through the ozone water
supply line portion 105-5 is measured by the pressure gauge 132,
the temperature is measured by the thermocouple 115, and the flow
rate is measured by the flow meter 116, as necessary.
The concentration of ozone water flowing through the point A on the
ozone water supply line portion 1051-1 is measured by an ozone
water concentration meter 112.
In order for the concentration of the ozone water flowing through
the point A to become a predetermined concentration, the
concentration and the flow rate and the supply pressure of the
ozone gas flowing through the ozone gas supply line portion 106-1
and the flow rate and the supply pressure of the water solvent
flowing through the water solvent supply line portion 104-3 are
adjusted so as to have predetermined values in the ranges of the
above equations (1) to (7)
EXAMPLES
Experiments on examples and comparative examples supporting the
present invention using the ozone water production and supply
system apparatus shown in FIG. 1 were carried out as follows.
Experiment 1
An experiment was carried out under the following production
conditions. The results are shown in FIG. 3.
The horizontal axis represents the ozone gas (supply) pressure
(Po=P3) (MPa), and the vertical axis represents the ozone water
concentration (ppm).
[Production Conditions]
pH adjusting additive:
Hydrochloric acid, adjusted to a concentration of 0.24 wt % and
pH1.2 (at 22.degree. C.) Ultrapure water:
(Supply) Flow rate (F1) 1 L/min, (Supply) Pressure (P1=Pw) 0.25 MPa
Ozone gas:
(Supply) Concentration (N) 350 g/Nm3, (Supply) Flow rate (Fo=F3) 5
NL/min,
(Supply) Pressure (Po=P3) 0.01 to 0.24 MPa Chemical solution
temperature (T1) (heating temperature of ultrapure water after pH
adjustment and before ozone gas dissolution) 80.degree. C.
As shown in FIG. 3, the ozone gas (supply) pressure (Po=P3)
dependence of the ozone water concentration (dissolved
concentration of ozone) shows greatly different results between
pressure regions of greater than 0.15 MP and less than 0.15 MP. In
other words, in terms of increase rate of the ozone water
concentration, it has been shown that the increase rate of the
ozone water concentration in the range of 0.15 MP or more in the
ozone gas (supply) pressure (Po=P3) is much larger than the
increase rate of the ozone water concentration in the range of 0.15
MP or less in the ozone gas (supply) pressure (Po=P3).
Moreover, the result is that ozone water having an ozone water
concentration of about 650 ppm is obtained at a chemical solution
temperature of 80.degree. C. and an ozone gas supply pressure of
0.24 MPa.
Experiment 2
An experiment was carried out under the following production
conditions. The results are shown in FIG. 4.
The horizontal axis represents the ozone gas (supply) pressure
(Po=P3) (MP), and the vertical axis represents the ozone water
concentration (ppm).
[Production Conditions]
pH adjusting additive: Citric acid, adjusted to a concentration of
1.0 wt %, and pH 2.2 (at 22.degree. C.) Ultrapure water: (Supply)
Flow rate (F1) 1 L/min, (Supply) Pressure (P1=Pw) 0.25 MPa Ozone
gas; (Supply) Concentration (N) 350 g/Nm3, (Supply) Flow rate
(Fo=F3) 5 NL/min, Supply pressure (P3) 0.01 to 0.24 MPa Chemical
solution temperature (T1) (heating temperature of ultrapure water
after pH adjustment and before ozone gas dissolution) 80.degree.
C.
As shown in FIG. 4, the ozone gas (supply) pressure (Po=P3)
dependence of the ozone water concentration (dissolved
concentration of ozone) shows greatly different results between
pressure regions of 0.15 MP or less and greater than 0.15 MP. In
other words, in terms of increase rate of the ozone water
concentration, it has been shown that the increase rate of the
ozone water concentration in the range of 0.15 MP in the ozone gas
(supply) pressure (Po=P3) is much larger than the increase rate of
the ozone water concentration in the range of 0.15 MP or less in
the ozone gas (supply) pressure (Po=P3).
Moreover, the result is that ozone water having an ozone water
concentration of about 750 ppm is obtained at a chemical solution
temperature of 80.degree. C. and an ozone gas supply pressure of
0.24 MPa.
Experiment 3
An experiment was carried out under the following production
conditions. The results are shown in FIG. 5.
The horizontal axis represents the ozone gas (supply) pressure
(Po=P3) (MP), and the vertical axis represents the ozone water
concentration (ppm).
[Production Conditions]
pH adjusting additive: acetic acid Concentration 12.0 wt %, pH2.2
(at 22.degree. C.) Ultrapure water flow rate (F1) 1 L/min, pressure
(P1) 0.25 MPa Ozone gas
(Supply) Concentrations 350 g/Nm3, (Supply) Flow rate 5 NL/min
(Supply) Pressure (P3) 0.01 to 0.24 MPa Chemical solution
temperature (T1) (heating temperature of ultrapure water after pH
adjustment and before ozone gas dissolution) 80.degree. C.
As shown in FIG. 5, the ozone gas (supply) pressure (Po=P3)
dependence of the ozone water concentration (dissolved
concentration of ozone) shows greatly different results between
pressure regions of 0.15 MP or less and greater than 0.15 MP. In
other words, in terms of increase rate of the ozone water
concentration, it has been shown that the increase rate of the
ozone water concentration in the range of 0.15 MP in the ozone gas
(supply) pressure (Po=P3) is much larger than in the increase rate
of the ozone water concentration in the range of 0.15 MP or less in
the ozone gas (supply) pressure (Po=P3).
Moreover, the result is that ozone water having an ozone water
concentration of about 850 ppm is obtained at a chemical solution
temperature of 80.degree. C. and an ozone gas supply pressure of
0.24 MPa.
In the following Experiments 4-6, ozone waters were produced to
conduct experiments to confirm their resist removal effects. As
substrates to be processed, semiconductor substrates each having a
surface on which a resist (a KrF-positive resist TDUR-P3116EM 15cp
manufactured by Tokyo Ohka Kogyo Co., Ltd., pre-baking at
90.degree. C. for 90 seconds, post-baking at 110.degree. C. for 90
seconds, and a film thickness of 750 nanometers) was applied by a
spinner were used.
Experiment 4
An experiment for confirming the effect of resist removal was
carried out using ozone water prepared under the following
production conditions. The results are shown in FIG. 6.
The horizontal axis represents the ozonized water concentration
(ppm), and the vertical axis represents the resist removal rate
(nm/min).
[Ozone Water Production Conditions]
pH adjusting additive: hydrochloric acid Concentration 0.24 wt. %,
pH1.2 (at 22.degree. C.) Ultrapure water flow rate (F1) 1 L/min,
pressure (P1) 0.25 MPa Ozone gas: (Supply) Concentrations 350
g/Nm3, (Supply) Flow rate 5 NL/min (Supply) Pressure (P3) 0.01 to
0.24 MPa The ultrapure water is heated so that the temperature of
the chemical (ozone water) sprayed from the nozzle 122 becomes
80.degree. C. [Resist Removal Conditions] The ozone water produced
under the above production conditions was sprayed from the nozzle
122 onto the resist coating surface of the substrate to be
processed. Temperature of the chemical (ozone water) sprayed from
the nozzle 122: 80.degree. C. Measured with a nozzle thermometer
(T3) 117 During processing, hot water is sprayed onto the back
surface of the substrate to be processed (the surface on which the
resist is not applied) Temperature of hot water 90.degree. C.,
spray flow rate 3 L/min The results are shown in FIG. 6. As shown
in FIG. 6, in the range of ozone water concentration of 400-600
ppm, the results of extremely high resist removal effect with
resist removal rate of 2000-2200 nm/min were obtained.
Experiment 5
An experiment for confirming the effect of resist removal was
carried out using ozone water prepared under the following
production conditions. The results are shown in FIG. 7.
The horizontal axis represents the ozonized water concentration
(ppm), and the vertical axis represents the resist removal rate
(nm/min).
[Ozone Water Production Conditions]
pH adjusting additive: citric acid Concentration 1.0 wt %, pH2.2
(at 22.degree. C.) Ultrapure water: Flow rate (F1) 1 L/min,
Pressure (P1) 0.25 MPa Ozone gas: (Supply) Concentrations 350
g/Nm3, (Supply) Flow rate 5 NL/min (Supply) Pressure (P3) 0.01 to
0.24 MPa The ultrapure water is heated so that the temperature of
the chemical (ozone water) sprayed from the nozzle 122 becomes
80.degree. C. [Resist Removal Conditions] The ozone water produced
under the above production conditions was sprayed from the nozzle
122 onto the resist coating surface of the substrate to be
processed. Temperature of the chemical (ozone water) sprayed from
the nozzle 122: 80.degree. C. Measured with a nozzle thermometer
(T3) 117 During processing, hot water is sprayed onto the back
surface (the surface on which the resist is not applied) of the
substrate to be processed. Temperature of hot water 90.degree. C.,
spray flow rate 3 L/min The results are shown in FIG. 7. As shown
in FIG. 7, in the range of ozone water concentration of 400-600
ppm, the results of extremely high resist removal effect with
resist removal rate of 1600-1800 nm/min were obtained.
Experiment 6
An experiment for confirming the effect of resist removal was
carried out using ozone water prepared under the following process
conditions. The results are shown in FIG. 8. The horizontal axis
represents the ozonize water concentration (ppm), and the vertical
axis represents the resist removal rate (nm/min).
[Ozone Water Production Conditions]
pH adjusting additive: acetic acid Concentration 1.0 wt %, pH2.2
(at 22.degree. C.) Ultrapure water: Flow rate (F1) 1 L/min,
Pressure (P1) 0.25 MPa Ozone gas: (Supply) Concentrations 350
g/Nm3, (Supply) Flow rate 5 NL/min (Supply) Pressure (P3) 0.01 to
0.24 MPa The ultrapure water is heated so that the temperature of
the chemical (ozone water) sprayed from the nozzle 122 becomes
80.degree. C. [Resist Removal Conditions] The ozone water produced
under the above production conditions was sprayed from the nozzle
122 onto the resist coating surface of the substrate to be
processed. Temperature of the chemical (ozone water) sprayed from
the nozzle 122: 80.degree. C. Measured with a nozzle thermometer
(T3) 117 During processing, hot water is sprayed onto the back
surface of the substrate to be processed (the surface on which the
resist is not applied) Temperature of hot water 90.degree. C.,
spray flow rate 3 L/min The results are shown in FIG. 8. As shown
in FIG. 8, in the range of ozone water concentration 600 to 800
ppm, the results of extremely high resist removal effect around a
resist removal rate of 1600 nm/min was obtained. In the following
Experiments 7 and 8, ozone water was prepared, and experiments for
confirming the life thereof were carried out. In the experiments,
the ozone water supply line 105 was filled with the ozone water
produced by the ozone gas dissolving module unit 102, and then the
open-close valve 120 was closed to confine the ozone water in the
ozone water supply line portion 105-1, and measured the time change
of the ozone concentration by the ozone water concentration meters
112 and 114 in the confinement time range of from 0 to 300 seconds.
The ozone water concentration meter 112 was set at a position of
0.2 cm (measurement position at 0 sec: point A) from the ozone gas
dissolving device 102-1, and the ozone water concentration meter
114 was set at a position of 3 m (measurement position at 3 to 300
sec: point B) from the ozone gas dissolving device 102-1.
Experiment 7
As pH-adjusting additives, acetic acid, citric acid, and
hydrochloric acid were used to prepare chemical solutions of pH2.2
(22.degree. C.), respectively.
Experiment 7-1
pH-adjusting additive: acetic acid, concentration 120 wt %, pH2.2
(22.degree. C.)
Experiment 7-2
pH-adjusting additive: citric acid, concentration 1.0 wt %, pH2.2
(22.degree. C.)
Experiment 7-3
pH-adjusting additive: hydrochloric acid, concentration 0.02 wt %,
pH2.2 (22.degree. C.)
Other conditions were common to Experiments 7-1 to 7-3 as
follows.
Ultrapure water: Flow rate (F1) 1 L/min (measured by flow meter
108), Pressure (P2) 0.25 MPa (measured with pressure gauge 113)
Ozone gas: (Supply) Concentrations 380 g/Nm3, (Supply) Flow rate 5
NL/min (measured by ozonizer) (Supply) Pressure (P3) 0.24 MPa
(measured with pressure gauge 110) Chemical solution (ozone water)
temperature: 22.degree. C. The results are shown in FIG. 9. As
shown in FIG. 9, in the cases of acetic acid and citric acid, in
the initial state (0 seconds), ozone water of a quite high
concentration of 1100 ppm or more is obtained, and even after 300
seconds elapsed, an ozone water concentration of about 300 ppm is
maintained.
In comparison, in the case of hydrochloric acid, in the initial
state (0 seconds), the ozone water concentration is about 800 ppm,
and in addition, the ozone water concentration is attenuated to
about 100 ppm at an elapsed time of about 60 seconds.
In other words, as compared with the case of hydrochloric acid, in
the case of acetic acid and citric acid, it was confirmed by
experiments that a quite high concentration of ozone water can be
obtained, and moreover, a high concentration can be maintained for
a suitable long time.
This infers that acetic acid and citric acid are much better than
hydrochloric acid in the decomposition suppressing power of ozone
in ozone water.
From the result of FIG. 9, it can be confirmed that in the case of
acetic acid and citric acid, if ozone water treatment is carried
out in the position within the elapsed time of 50 seconds, the
treatment can be performed with high-concentration ozone water of
about 600 ppm or more.
Experiment 8
Experiments were carried out under the same conditions as in
Experiment 7, except that the chemical solution (ozone water)
temperature was set at 80.degree. C.
The results are shown in FIG. 10.
As FIG. 10 shows, despite the high temperature of 80.degree. C.,
high-temperature high-concentration ozone waters are obtained in
which the ozone water concentration at the initial state (0
seconds) is more than 600 ppm in hydrochloric acid, about 750 ppm
in citric acid, and about 850 ppm in acetic acid.
In the cases of acetic acid and citric acid, the ozone water
concentration of about 300 ppm is maintained even around an elapsed
time of 90 seconds.
This infers that acetic acid and citric acid have considerable
degree of decomposition suppressing power of ozone even in the case
of high temperature ozone water.
In comparison, in the case of hydrochloric acid, the ozone water
concentration has already attenuated to about 100 ppm at about 60
seconds elapsed.
In other words, it was confirmed by experiments that in the cases
of acetic acid and citric acid, higher-temperature
higher-concentration ozone water than the case of hydrochloric acid
can be obtained, and moreover, the high concentration can be
maintained for longer time.
This seems to indicate that acetic acid and citric acid are much
better than hydrochloric acid in the decomposition suppressing
power of ozone in water even in high-temperature ozone water.
From the result of FIG. 10, it can be confirmed that in the case of
acetic acid and citric acid, if ozone water treatment is carried
out at the position within an elapsed time of 100 seconds or less,
the treatment can be performed reliably with high-temperature
high-concentration ozone water of about 300 ppm or more.
Experiment 9
Experiments to investigate pH dependence of ozone water
concentration using various pH adjusting additives were carried out
under the following production conditions:
[Ozone Water Production Conditions]
Ultrapure water: (Supply) Flow rate (F1) 1 L/min, (Supply) Pressure
(P2) 0.25 MPa Ozone gas: (Supply) Concentration (N) 350 g/Nm3,
(Supply) Flow rate (Fo) 5 NL/min (Supply) Pressure (P3) 0.2 MPa
Chemical solution temperature: 22.degree. C. The results are shown
in FIG. 11. FIG. 11 also describes for reference, an example of
carbon dioxide addition as a pH adjusting additive. As can be seen
from the data shown in FIG. 11, when the values of the respective
production parameters are set to values within the ranges of the
above-mentioned equations (1) to (7) and are set to pH4 or less,
high-concentration ozone water of about 350 ppm or more can be
obtained.
Experiment 10
Experiments regarding the dependence of the ozone water
concentration on the ozone gas supply flow rate were carried out
under the following production conditions.
[Ozone Water Production Conditions]
pH adjusting additive: citric acid Concentration 1.0 wt %, pH2.2
(at 22.degree. C.) Ultrapure water: (Supply) Flow rate (F1) 1
L/min, (Supply) Pressure (P1) 0.30 MPa, (P2) 0.25 MPa Ozone gas:
(Supply) Pressure (P3) 0.24 MPa (Supply) Concentrations (N) g/Nm3,
(Supply) Flow Rate (Fo) NL/min is shown in Table 1 below. Chemical
solution temperature: 22.degree. C.
TABLE-US-00001 TABLE 1 Ozone gas Ozone water Ozone gas flow rate
concentration concentration [NL/min] [g/Nm3] [ppm] 0.5 390 339 2
360 553 3 350 674 4 340 783 5 330 822 6 320 756 7 300 678
The results are shown in FIG. 12. As shown in FIG. 12, when the
ozone gas flow rate is 0.25 NL/min or more, ozone water having an
ozone water concentration of about 340 ppm or more can be obtained.
When the ozone gas flow rate is near 5 NL/min, a peak is seen in
the ozone water concentration, and when the ozone gas flow rate
exceeds the value at the peak, and the ozone water concentration
decreases slowly. As an upper limit value of the flow rate of the
ozone gas is 80 NL/min on the assumption that ozone water having an
ozone water concentration of 300 ppm or more is obtained.
Experiment 11
An experiment regarding the dependence of the ozone water
concentration on the ultrapure water supply flow rate was carried
out under the following production conditions.
[Ozone Water Production Conditions]
pH adjusting additive: citric acid Concentration 1.0 wt % pH2.2
(22.degree. C.) Ultrapure water (Supply) flow rate (F1) L/min is
shown in Table 2 below. (Supply) Pressure (P1) 0.30 MPa (P2) 0.25
MPa Ozone gas: ((Supply) Concentrations 350 g/Nm3 (Supply) Flow
rate 5 NL/min (Supply) Pressure (P3) 0.24 MPa
TABLE-US-00002 TABLE 2 Ultrapure water flow rate Ozone water
concentration [L/min] [ppm] 0.5 986 1 822 2 523 3 430 4 397 5
360
Results are shown in FIG. 13. As shown in FIG. 13, the lower the
flow rate of ultrapure water, the higher the concentration of ozone
water obtained, but from the viewpoint of precisely and easily
controlling the flow rate, the lower limit value is set to 0.5
L/min or more. In terms of upper limit value of the flow rate of
ultrapure water, in order to efficiently obtain ozone water having
a desired ozone concentration, it is determined by optimizing the
balance between the dissolution efficiency of ozone and the
production efficiency of ozone water, but in order to obtain ozone
water having an ozone concentration of 300 ppm or more, it is
desirable to set it to 40 L/min or less.
Experiment 12
In the ozone water production and supply system 100 shown in FIG.
1, a heating means similar to the heating means 123 is provided in
a portion of the ozone water supply line portion 105-1 between the
ozone gas dissolving module unit 102 and the ozone water supply
module unit 103, thereby producing an ozone water production and
supply system which is also a post-heating type. The following
experiments were carried out using this newly prepared ozone water
production and supply system.
(1) Experiment 12-1
In Experiment 1, a series of high-temperature high-concentration
ozone water samples were prepared under the same production
conditions as in Experiment 1, except that ozone water
(low-temperature ozone water) having a liquid temperature of
22.degree. C. was prepared in advance, and then this ozone water
was heated to 80.degree. C.
As a result, although the ozone water concentration is slightly
lower in each sample than in the results shown in FIG. 4, the ozone
gas pressure dependence of ozone water concentration having the
tendency shown in FIG. 2 was obtained.
(2) Experiment 12-2
In Experiment 2, a series of high-temperature and
high-concentration ozone water samples were prepared under the same
production conditions as in Experiment 2, except that ozone water
(low-temperature ozone water) having a liquid temperature of
22.degree. C. was prepared in advance, and then this ozone water
was heated to 80.degree. C.
As a result, although the ozone water concentration is slightly
lower in each sample than in the results shown in FIG. 3, the ozone
gas pressure dependence of ozone water concentration having the
tendency shown in FIG. 2 was obtained.
(3) Experiment 12-3
In Experiment 3, a series of high-temperature and
high-concentration ozone water samples were prepared under the same
production conditions as in Experiment 1, except that ozone water
(low-temperature ozone water) having a liquid temperature of
22.degree. C. was prepared in advance, and then this ozone water
was heated to 80.degree. C.
As a result, although the ozone water concentration was slightly
lower in each sample than in the results shown in FIG. 5, the ozone
gas pressure dependence of ozone water concentration having the
tendency shown in FIG. 2 was obtained.
Experiment 13
Experiments were conducted with one or more of the parameters shown
in the above equations (1) to (7) deviated from the numerical range
shown in equations (1) to (7). The number of samples was 100.
It was found from this experiment that the tendency shown in FIG. 2
was not observed when the ozone water was prepared with one or more
of the parameters shown in the above-mentioned equations (1) to (7)
deviated from the numerical range shown in the equations (1) to
(7).
In addition, it was observed that the tendency became more distant
from one shown in FIG. 2 as the number of parameters among the
parameters shown in the equations (1) to (7) deviating from the
numerical range shown the equations (1) to (7) increased.
Although the application of the present invention to the
semiconductor field has been described above, the application of
the present invention is not limited to the application to the
semiconductor field, but is also applicable to cleaning of
foodstuffs, cleaning of processing facilities and instruments,
cleaning of fingers, and the like, and deodorization,
sterilization, and preservation of freshness of foodstuffs.
In some applications, the concentration of ozone water is properly
diluted and used.
The present invention is not limited to the above embodiments, and
various changes and modifications can be made without departing
from the spirit and scope of the present invention. Therefore, in
order to make the scope of the present invention publicly
available, an attachment is attached which sets forth the
claims.
REFERENCE SIGNS LIST
100: Ozone water production and supply system 101: Hot water
production module unit 101-1: pH adjustment unit 101-2: Heating
unit 102: Ozone gas dissolving module unit 102-1: Ozone gas
dissolving device 103: Ozone water supply module unit 104: Water
solvent supply line 104-1.about.104-3: Water solvent supply line
portion 105: Ozone water supply line 105-1.about.105-6: Ozone water
supply line portion 106: Ozone gas supply line 106-1.about.106-3:
Ozone gas supply line portion 107: Ozone gas dissolving means 108:
Flow meter (F1) 109: Thermocouple (T1) 110: Pressure gauge (P3)
111-1: Pressure gauge (P0) 111-2: Pressure gauge (P1) 112: Ozone
water concentration meter (point A) 113: Pressure gauge (P2) 114:
Ozone water concentration meter (point B) 115: Thermocouple (T2)
116: Flow meter (F2) 117: Nozzle thermometer (T3) 118: Pressure
regulating valve 119: Three-way open-close valve 120: Open-close
valve 121: Open-close valve 122: Nozzle 123: Heating means 124:
Chemical solution tank 125: Chemical supply line 125-1.about.125-3:
Chemical supply line portion 126: Pump 127: Flow rate adjustment
valve 128: Static mixer 129: Conductivity meter 130: Chemical
supply device 131: Pressure gauge (P4) 132: Pressure gauge (P5)
133: Flowmeter (F3) 134: pH meter
* * * * *
References